IPVS: Extend scheduling functions for IPv6 support
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / Documentation / kernel-parameters.txt
1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
3
4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
8
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
31
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
104
105 In addition, the following text indicates that the option:
106
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
110
111 Parameters denoted with BOOT are actually interpreted by the boot
112 loader, and have no meaning to the kernel directly.
113 Do not modify the syntax of boot loader parameters without extreme
114 need or coordination with <Documentation/i386/boot.txt>.
115
116 There are also arch-specific kernel-parameters not documented here.
117 See for example <Documentation/x86_64/boot-options.txt>.
118
119 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120 a trailing = on the name of any parameter states that that parameter will
121 be entered as an environment variable, whereas its absence indicates that
122 it will appear as a kernel argument readable via /proc/cmdline by programs
123 running once the system is up.
124
125 The number of kernel parameters is not limited, but the length of the
126 complete command line (parameters including spaces etc.) is limited to
127 a fixed number of characters. This limit depends on the architecture
128 and is between 256 and 4096 characters. It is defined in the file
129 ./include/asm/setup.h as COMMAND_LINE_SIZE.
130
131
132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
134 Format: { force | off | ht | strict | noirq }
135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
139 strict -- Be less tolerant of platforms that are not
140 strictly ACPI specification compliant.
141
142 See also Documentation/power/pm.txt, pci=noacpi
143
144 acpi_apic_instance= [ACPI, IOAPIC]
145 Format: <int>
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
148 default: 0
149
150 acpi_sleep= [HW,ACPI] Sleep options
151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
160 used by default).
161
162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
163 Format: { level | edge | high | low }
164
165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
167 default in APIC mode
168
169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
171 default in PIC mode
172
173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
174 use by PCI
175 Format: <irq>,<irq>...
176
177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
178 Format: <irq>,<irq>...
179
180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
181
182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
184
185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
189
190 acpi_serialize [HW,ACPI] force serialization of AML methods
191
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
198 HPET
199
200 acpi.debug_layer= [HW,ACPI]
201 Format: <int>
202 Each bit of the <int> indicates an ACPI debug layer,
203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
216
217 acpi.debug_level= [HW,ACPI]
218 Format: <int>
219 Each bit of the <int> indicates an ACPI debug level,
220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
234
235 acpi_pm_good [X86-32,X86-64]
236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
239
240 agp= [AGP]
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
245
246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
250 The kernel tries to set a reasonable default.
251
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
255
256 ad1848= [HW,OSS]
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
258
259 advansys= [HW,SCSI]
260 See header of drivers/scsi/advansys.c.
261
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
264
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
268
269 aha152x= [HW,SCSI]
270 See Documentation/scsi/aha152x.txt.
271
272 aha1542= [HW,SCSI]
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
274
275 aic7xxx= [HW,SCSI]
276 See Documentation/scsi/aic7xxx.txt.
277
278 aic79xx= [HW,SCSI]
279 See Documentation/scsi/aic79xx.txt.
280
281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
283 Possible values are:
284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
286 domain)
287 amd_iommu_size= [HW,X86-64]
288 Define the size of the aperture for the AMD IOMMU
289 driver. Possible values are:
290 '32M', '64M' (default), '128M', '256M', '512M', '1G'
291
292 amijoy.map= [HW,JOY] Amiga joystick support
293 Map of devices attached to JOY0DAT and JOY1DAT
294 Format: <a>,<b>
295 See also Documentation/kernel/input/joystick.txt
296
297 analog.map= [HW,JOY] Analog joystick and gamepad support
298 Specifies type or capabilities of an analog joystick
299 connected to one of 16 gameports
300 Format: <type1>,<type2>,..<type16>
301
302 apc= [HW,SPARC]
303 Power management functions (SPARCstation-4/5 + deriv.)
304 Format: noidle
305 Disable APC CPU standby support. SPARCstation-Fox does
306 not play well with APC CPU idle - disable it if you have
307 APC and your system crashes randomly.
308
309 apic= [APIC,i386] Advanced Programmable Interrupt Controller
310 Change the output verbosity whilst booting
311 Format: { quiet (default) | verbose | debug }
312 Change the amount of debugging information output
313 when initialising the APIC and IO-APIC components.
314
315 apm= [APM] Advanced Power Management
316 See header of arch/x86/kernel/apm_32.c.
317
318 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
319 Format: <io>,<irq>,<nodeID>
320
321 ataflop= [HW,M68k]
322
323 atarimouse= [HW,MOUSE] Atari Mouse
324
325 atascsi= [HW,SCSI] Atari SCSI
326
327 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
328 EzKey and similar keyboards
329
330 atkbd.reset= [HW] Reset keyboard during initialization
331
332 atkbd.set= [HW] Select keyboard code set
333 Format: <int> (2 = AT (default), 3 = PS/2)
334
335 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
336 keyboards
337
338 atkbd.softraw= [HW] Choose between synthetic and real raw mode
339 Format: <bool> (0 = real, 1 = synthetic (default))
340
341 atkbd.softrepeat= [HW]
342 Use software keyboard repeat
343
344 autotest [IA64]
345
346 baycom_epp= [HW,AX25]
347 Format: <io>,<mode>
348
349 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
350 Format: <io>,<mode>
351 See header of drivers/net/hamradio/baycom_par.c.
352
353 baycom_ser_fdx= [HW,AX25]
354 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
355 Format: <io>,<irq>,<mode>[,<baud>]
356 See header of drivers/net/hamradio/baycom_ser_fdx.c.
357
358 baycom_ser_hdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
360 Format: <io>,<irq>,<mode>
361 See header of drivers/net/hamradio/baycom_ser_hdx.c.
362
363 boot_delay= Milliseconds to delay each printk during boot.
364 Values larger than 10 seconds (10000) are changed to
365 no delay (0).
366 Format: integer
367
368 bootmem_debug [KNL] Enable bootmem allocator debug messages.
369
370 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
371 bttv.radio= Most important insmod options are available as
372 kernel args too.
373 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
374 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
375
376 BusLogic= [HW,SCSI]
377 See drivers/scsi/BusLogic.c, comment before function
378 BusLogic_ParseDriverOptions().
379
380 c101= [NET] Moxa C101 synchronous serial card
381
382 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
383 Sometimes CPU hardware bugs make them report the cache
384 size incorrectly. The kernel will attempt work arounds
385 to fix known problems, but for some CPUs it is not
386 possible to determine what the correct size should be.
387 This option provides an override for these situations.
388
389 security= [SECURITY] Choose a security module to enable at boot.
390 If this boot parameter is not specified, only the first
391 security module asking for security registration will be
392 loaded. An invalid security module name will be treated
393 as if no module has been chosen.
394
395 capability.disable=
396 [SECURITY] Disable capabilities. This would normally
397 be used only if an alternative security model is to be
398 configured. Potentially dangerous and should only be
399 used if you are entirely sure of the consequences.
400
401 ccw_timeout_log [S390]
402 See Documentation/s390/CommonIO for details.
403
404 cgroup_disable= [KNL] Disable a particular controller
405 Format: {name of the controller(s) to disable}
406 {Currently supported controllers - "memory"}
407
408 checkreqprot [SELINUX] Set initial checkreqprot flag value.
409 Format: { "0" | "1" }
410 See security/selinux/Kconfig help text.
411 0 -- check protection applied by kernel (includes
412 any implied execute protection).
413 1 -- check protection requested by application.
414 Default value is set via a kernel config option.
415 Value can be changed at runtime via
416 /selinux/checkreqprot.
417
418 cio_ignore= [S390]
419 See Documentation/s390/CommonIO for details.
420
421 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
422 [Deprecated]
423 Forces specified clocksource (if available) to be used
424 when calculating gettimeofday(). If specified
425 clocksource is not available, it defaults to PIT.
426 Format: { pit | tsc | cyclone | pmtmr }
427
428 clocksource= [GENERIC_TIME] Override the default clocksource
429 Format: <string>
430 Override the default clocksource and use the clocksource
431 with the name specified.
432 Some clocksource names to choose from, depending on
433 the platform:
434 [all] jiffies (this is the base, fallback clocksource)
435 [ACPI] acpi_pm
436 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
437 pxa_timer,timer3,32k_counter,timer0_1
438 [AVR32] avr32
439 [X86-32] pit,hpet,tsc,vmi-timer;
440 scx200_hrt on Geode; cyclone on IBM x440
441 [MIPS] MIPS
442 [PARISC] cr16
443 [S390] tod
444 [SH] SuperH
445 [SPARC64] tick
446 [X86-64] hpet,tsc
447
448 clearcpuid=BITNUM [X86]
449 Disable CPUID feature X for the kernel. See
450 include/asm-x86/cpufeature.h for the valid bit numbers.
451 Note the Linux specific bits are not necessarily
452 stable over kernel options, but the vendor specific
453 ones should be.
454 Also note that user programs calling CPUID directly
455 or using the feature without checking anything
456 will still see it. This just prevents it from
457 being used by the kernel or shown in /proc/cpuinfo.
458 Also note the kernel might malfunction if you disable
459 some critical bits.
460
461 code_bytes [IA32/X86_64] How many bytes of object code to print
462 in an oops report.
463 Range: 0 - 8192
464 Default: 64
465
466 disable_8254_timer
467 enable_8254_timer
468 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
469 over the 8254 in addition to over the IO-APIC. The
470 kernel tries to set a sensible default.
471
472 hpet= [X86-32,HPET] option to control HPET usage
473 Format: { enable (default) | disable | force }
474 disable: disable HPET and use PIT instead
475 force: allow force enabled of undocumented chips (ICH4,
476 VIA, nVidia)
477
478 com20020= [HW,NET] ARCnet - COM20020 chipset
479 Format:
480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
481
482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
483 Format: <io>[,<irq>]
484
485 com90xx= [HW,NET]
486 ARCnet - COM90xx chipset (memory-mapped buffers)
487 Format: <io>[,<irq>[,<memstart>]]
488
489 condev= [HW,S390] console device
490 conmode=
491
492 console= [KNL] Output console device and options.
493
494 tty<n> Use the virtual console device <n>.
495
496 ttyS<n>[,options]
497 ttyUSB0[,options]
498 Use the specified serial port. The options are of
499 the form "bbbbpnf", where "bbbb" is the baud rate,
500 "p" is parity ("n", "o", or "e"), "n" is number of
501 bits, and "f" is flow control ("r" for RTS or
502 omit it). Default is "9600n8".
503
504 See Documentation/serial-console.txt for more
505 information. See
506 Documentation/networking/netconsole.txt for an
507 alternative.
508
509 uart[8250],io,<addr>[,options]
510 uart[8250],mmio,<addr>[,options]
511 Start an early, polled-mode console on the 8250/16550
512 UART at the specified I/O port or MMIO address,
513 switching to the matching ttyS device later. The
514 options are the same as for ttyS, above.
515
516 If the device connected to the port is not a TTY but a braille
517 device, prepend "brl," before the device type, for instance
518 console=brl,ttyS0
519 For now, only VisioBraille is supported.
520
521 earlycon= [KNL] Output early console device and options.
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address.
526 The options are the same as for ttyS, above.
527
528 no_console_suspend
529 [HW] Never suspend the console
530 Disable suspending of consoles during suspend and
531 hibernate operations. Once disabled, debugging
532 messages can reach various consoles while the rest
533 of the system is being put to sleep (ie, while
534 debugging driver suspend/resume hooks). This may
535 not work reliably with all consoles, but is known
536 to work with serial and VGA consoles.
537
538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
539 Format:
540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
541
542 crashkernel=nn[KMG]@ss[KMG]
543 [KNL] Reserve a chunk of physical memory to
544 hold a kernel to switch to with kexec on panic.
545
546 crashkernel=range1:size1[,range2:size2,...][@offset]
547 [KNL] Same as above, but depends on the memory
548 in the running system. The syntax of range is
549 start-[end] where start and end are both
550 a memory unit (amount[KMG]). See also
551 Documentation/kdump/kdump.txt for a example.
552
553 cs4232= [HW,OSS]
554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
555
556 cs89x0_dma= [HW,NET]
557 Format: <dma>
558
559 cs89x0_media= [HW,NET]
560 Format: { rj45 | aui | bnc }
561
562 dasd= [HW,NET]
563 See header of drivers/s390/block/dasd_devmap.c.
564
565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
566 (one device per port)
567 Format: <port#>,<type>
568 See also Documentation/input/joystick-parport.txt
569
570 debug [KNL] Enable kernel debugging (events log level).
571
572 debug_locks_verbose=
573 [KNL] verbose self-tests
574 Format=<0|1>
575 Print debugging info while doing the locking API
576 self-tests.
577 We default to 0 (no extra messages), setting it to
578 1 will print _a lot_ more information - normally
579 only useful to kernel developers.
580
581 debug_objects [KNL] Enable object debugging
582
583 debugpat [X86] Enable PAT debugging
584
585 decnet.addr= [HW,NET]
586 Format: <area>[,<node>]
587 See also Documentation/networking/decnet.txt.
588
589 vt.default_blu= [VT]
590 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
591 Change the default blue palette of the console.
592 This is a 16-member array composed of values
593 ranging from 0-255.
594
595 vt.default_grn= [VT]
596 Format: <green0>,<green1>,<green2>,...,<green15>
597 Change the default green palette of the console.
598 This is a 16-member array composed of values
599 ranging from 0-255.
600
601 vt.default_red= [VT]
602 Format: <red0>,<red1>,<red2>,...,<red15>
603 Change the default red palette of the console.
604 This is a 16-member array composed of values
605 ranging from 0-255.
606
607 vt.default_utf8=
608 [VT]
609 Format=<0|1>
610 Set system-wide default UTF-8 mode for all tty's.
611 Default is 1, i.e. UTF-8 mode is enabled for all
612 newly opened terminals.
613
614 dhash_entries= [KNL]
615 Set number of hash buckets for dentry cache.
616
617 digi= [HW,SERIAL]
618 IO parameters + enable/disable command.
619
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/digiepca.txt.
623
624 disable_mtrr_cleanup [X86]
625 enable_mtrr_cleanup [X86]
626 The kernel tries to adjust MTRR layout from continuous
627 to discrete, to make X server driver able to add WB
628 entry later. This parameter enables/disables that.
629
630 mtrr_chunk_size=nn[KMG] [X86]
631 used for mtrr cleanup. It is largest continous chunk
632 that could hold holes aka. UC entries.
633
634 mtrr_gran_size=nn[KMG] [X86]
635 Used for mtrr cleanup. It is granularity of mtrr block.
636 Default is 1.
637 Large value could prevent small alignment from
638 using up MTRRs.
639
640 mtrr_spare_reg_nr=n [X86]
641 Format: <integer>
642 Range: 0,7 : spare reg number
643 Default : 1
644 Used for mtrr cleanup. It is spare mtrr entries number.
645 Set to 2 or more if your graphical card needs more.
646
647 disable_mtrr_trim [X86, Intel and AMD only]
648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
652
653 dmasound= [HW,OSS] Sound subsystem buffers
654
655 dscc4.setup= [NET]
656
657 dtc3181e= [HW,SCSI]
658
659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
660 earlyprintk=vga
661 earlyprintk=serial[,ttySn[,baudrate]]
662
663 Append ",keep" to not disable it when the real console
664 takes over.
665
666 Only vga or serial at a time, not both.
667
668 Currently only ttyS0 and ttyS1 are supported.
669
670 Interaction with the standard serial driver is not
671 very good.
672
673 The VGA output is eventually overwritten by the real
674 console.
675
676 eata= [HW,SCSI]
677
678 edd= [EDD]
679 Format: {"off" | "on" | "skip[mbr]"}
680
681 eisa_irq_edge= [PARISC,HW]
682 See header of drivers/parisc/eisa.c.
683
684 elanfreq= [X86-32]
685 See comment before function elanfreq_setup() in
686 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
687
688 elevator= [IOSCHED]
689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
690 See Documentation/block/as-iosched.txt and
691 Documentation/block/deadline-iosched.txt for details.
692
693 elfcorehdr= [X86-32, X86_64]
694 Specifies physical address of start of kernel core
695 image elf header. Generally kexec loader will
696 pass this option to capture kernel.
697 See Documentation/kdump/kdump.txt for details.
698
699 enforcing [SELINUX] Set initial enforcing status.
700 Format: {"0" | "1"}
701 See security/selinux/Kconfig help text.
702 0 -- permissive (log only, no denials).
703 1 -- enforcing (deny and log).
704 Default value is 0.
705 Value can be changed at runtime via /selinux/enforce.
706
707 es1371= [HW,OSS]
708 Format: <spdif>,[<nomix>,[<amplifier>]]
709 See also header of sound/oss/es1371.c.
710
711 ether= [HW,NET] Ethernet cards parameters
712 This option is obsoleted by the "netdev=" option, which
713 has equivalent usage. See its documentation for details.
714
715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
716 Format: <io>[,<irq>]
717
718 failslab=
719 fail_page_alloc=
720 fail_make_request=[KNL]
721 General fault injection mechanism.
722 Format: <interval>,<probability>,<space>,<times>
723 See also /Documentation/fault-injection/.
724
725 fd_mcs= [HW,SCSI]
726 See header of drivers/scsi/fd_mcs.c.
727
728 fdomain= [HW,SCSI]
729 See header of drivers/scsi/fdomain.c.
730
731 floppy= [HW]
732 See Documentation/floppy.txt.
733
734 force_pal_cache_flush
735 [IA-64] Avoid check_sal_cache_flush which may hang on
736 buggy SAL_CACHE_FLUSH implementations. Using this
737 parameter will force ia64_sal_cache_flush to call
738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
739
740 gamecon.map[2|3]=
741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
742 support via parallel port (up to 5 devices per port)
743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
744 See also Documentation/input/joystick-parport.txt
745
746 gamma= [HW,DRM]
747
748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
749 Format: off | on
750 default: on
751
752 gdth= [HW,SCSI]
753 See header of drivers/scsi/gdth.c.
754
755 gpt [EFI] Forces disk with valid GPT signature but
756 invalid Protective MBR to be treated as GPT.
757
758 gvp11= [HW,SCSI]
759
760 hashdist= [KNL,NUMA] Large hashes allocated during boot
761 are distributed across NUMA nodes. Defaults on
762 for IA-64, off otherwise.
763 Format: 0 | 1 (for off | on)
764
765 hcl= [IA-64] SGI's Hardware Graph compatibility layer
766
767 hd= [EIDE] (E)IDE hard drive subsystem geometry
768 Format: <cyl>,<head>,<sect>
769
770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
771 size of <nn>. This works even on boxes that have no
772 highmem otherwise. This also works to reduce highmem
773 size on bigger boxes.
774
775 highres= [KNL] Enable/disable high resolution timer mode.
776 Valid parameters: "on", "off"
777 Default: "on"
778
779 hisax= [HW,ISDN]
780 See Documentation/isdn/README.HiSax.
781
782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
784 On x86-64 and powerpc, this option can be specified
785 multiple times interleaved with hugepages= to reserve
786 huge pages of different sizes. Valid pages sizes on
787 x86-64 are 2M (when the CPU supports "pse") and 1G
788 (when the CPU supports the "pdpe1gb" cpuinfo flag)
789 Note that 1GB pages can only be allocated at boot time
790 using hugepages= and not freed afterwards.
791 default_hugepagesz=
792 [same as hugepagesz=] The size of the default
793 HugeTLB page size. This is the size represented by
794 the legacy /proc/ hugepages APIs, used for SHM, and
795 default size when mounting hugetlbfs filesystems.
796 Defaults to the default architecture's huge page size
797 if not specified.
798
799 i8042.direct [HW] Put keyboard port into non-translated mode
800 i8042.dumbkbd [HW] Pretend that controller can only read data from
801 keyboard and cannot control its state
802 (Don't attempt to blink the leds)
803 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
804 i8042.nokbd [HW] Don't check/create keyboard port
805 i8042.noloop [HW] Disable the AUX Loopback command while probing
806 for the AUX port
807 i8042.nomux [HW] Don't check presence of an active multiplexing
808 controller
809 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
810 controllers
811 i8042.panicblink=
812 [HW] Frequency with which keyboard LEDs should blink
813 when kernel panics (default is 0.5 sec)
814 i8042.reset [HW] Reset the controller during init and cleanup
815 i8042.unlock [HW] Unlock (ignore) the keylock
816
817 i810= [HW,DRM]
818
819 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
820 indicates that the driver is running on unsupported
821 hardware.
822 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
823 does not match list of supported models.
824 i8k.power_status
825 [HW] Report power status in /proc/i8k
826 (disabled by default)
827 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
828 capability is set.
829
830 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
831 See Documentation/mca.txt.
832
833 icn= [HW,ISDN]
834 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
835
836 ide= [HW] (E)IDE subsystem
837 Format: ide=nodma or ide=doubler
838 See Documentation/ide/ide.txt.
839
840 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
841 See Documentation/ide/ide.txt.
842
843 idle= [X86]
844 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
845 Poll forces a polling idle loop that can slightly improves the performance
846 of waking up a idle CPU, but will use a lot of power and make the system
847 run hot. Not recommended.
848 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
849 to not use it because it doesn't save as much power as a normal idle
850 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
851 as idle=poll.
852 idle=halt. Halt is forced to be used for CPU idle.
853 In such case C2/C3 won't be used again.
854 idle=nomwait. Disable mwait for CPU C-states
855
856 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
857 Claim all unknown PCI IDE storage controllers.
858
859 ignore_loglevel [KNL]
860 Ignore loglevel setting - this will print /all/
861 kernel messages to the console. Useful for debugging.
862
863 ihash_entries= [KNL]
864 Set number of hash buckets for inode cache.
865
866 in2000= [HW,SCSI]
867 See header of drivers/scsi/in2000.c.
868
869 init= [KNL]
870 Format: <full_path>
871 Run specified binary instead of /sbin/init as init
872 process.
873
874 initcall_debug [KNL] Trace initcalls as they are executed. Useful
875 for working out where the kernel is dying during
876 startup.
877
878 initrd= [BOOT] Specify the location of the initial ramdisk
879
880 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
881 Format: <irq>
882
883 inttest= [IA64]
884
885 iommu= [x86]
886 off
887 force
888 noforce
889 biomerge
890 panic
891 nopanic
892 merge
893 nomerge
894 forcesac
895 soft
896
897
898 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
899 off
900 Disable intel iommu driver.
901 igfx_off [Default Off]
902 By default, gfx is mapped as normal device. If a gfx
903 device has a dedicated DMAR unit, the DMAR unit is
904 bypassed by not enabling DMAR with this option. In
905 this case, gfx device will use physical address for
906 DMA.
907 forcedac [x86_64]
908 With this option iommu will not optimize to look
909 for io virtual address below 32 bit forcing dual
910 address cycle on pci bus for cards supporting greater
911 than 32 bit addressing. The default is to look
912 for translation below 32 bit and if not available
913 then look in the higher range.
914 strict [Default Off]
915 With this option on every unmap_single operation will
916 result in a hardware IOTLB flush operation as opposed
917 to batching them for performance.
918
919 io_delay= [X86-32,X86-64] I/O delay method
920 0x80
921 Standard port 0x80 based delay
922 0xed
923 Alternate port 0xed based delay (needed on some systems)
924 udelay
925 Simple two microseconds delay
926 none
927 No delay
928
929 io7= [HW] IO7 for Marvel based alpha systems
930 See comment before marvel_specify_io7 in
931 arch/alpha/kernel/core_marvel.c.
932
933 ip= [IP_PNP]
934 See Documentation/filesystems/nfsroot.txt.
935
936 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
937 See comment before ip2_setup() in
938 drivers/char/ip2/ip2base.c.
939
940 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
941 See header of drivers/scsi/ips.c.
942
943 ports= [IP_VS_FTP] IPVS ftp helper module
944 Default is 21.
945 Up to 8 (IP_VS_APP_MAX_PORTS) ports
946 may be specified.
947 Format: <port>,<port>....
948
949 irqfixup [HW]
950 When an interrupt is not handled search all handlers
951 for it. Intended to get systems with badly broken
952 firmware running.
953
954 irqpoll [HW]
955 When an interrupt is not handled search all handlers
956 for it. Also check all handlers each timer
957 interrupt. Intended to get systems with badly broken
958 firmware running.
959
960 isapnp= [ISAPNP]
961 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
962
963 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
964 Format:
965 <cpu number>,...,<cpu number>
966 or
967 <cpu number>-<cpu number> (must be a positive range in ascending order)
968 or a mixture
969 <cpu number>,...,<cpu number>-<cpu number>
970 This option can be used to specify one or more CPUs
971 to isolate from the general SMP balancing and scheduling
972 algorithms. The only way to move a process onto or off
973 an "isolated" CPU is via the CPU affinity syscalls.
974 <cpu number> begins at 0 and the maximum value is
975 "number of CPUs in system - 1".
976
977 This option is the preferred way to isolate CPUs. The
978 alternative -- manually setting the CPU mask of all
979 tasks in the system -- can cause problems and
980 suboptimal load balancer performance.
981
982 iucv= [HW,NET]
983
984 js= [HW,JOY] Analog joystick
985 See Documentation/input/joystick.txt.
986
987 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
988 specifies the amount of memory usable by the kernel
989 for non-movable allocations. The requested amount is
990 spread evenly throughout all nodes in the system. The
991 remaining memory in each node is used for Movable
992 pages. In the event, a node is too small to have both
993 kernelcore and Movable pages, kernelcore pages will
994 take priority and other nodes will have a larger number
995 of kernelcore pages. The Movable zone is used for the
996 allocation of pages that may be reclaimed or moved
997 by the page migration subsystem. This means that
998 HugeTLB pages may not be allocated from this zone.
999 Note that allocations like PTEs-from-HighMem still
1000 use the HighMem zone if it exists, and the Normal
1001 zone if it does not.
1002
1003 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1004 is similar to kernelcore except it specifies the
1005 amount of memory used for migratable allocations.
1006 If both kernelcore and movablecore is specified,
1007 then kernelcore will be at *least* the specified
1008 value but may be more. If movablecore on its own
1009 is specified, the administrator must be careful
1010 that the amount of memory usable for all allocations
1011 is not too small.
1012
1013 keepinitrd [HW,ARM]
1014
1015 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1016 in oops dumps.
1017
1018 kgdboc= [HW] kgdb over consoles.
1019 Requires a tty driver that supports console polling.
1020 (only serial suported for now)
1021 Format: <serial_device>[,baud]
1022
1023 l2cr= [PPC]
1024
1025 l3cr= [PPC]
1026
1027 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1028 disabled it.
1029
1030 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1031 C2 power state.
1032
1033 libata.dma= [LIBATA] DMA control
1034 libata.dma=0 Disable all PATA and SATA DMA
1035 libata.dma=1 PATA and SATA Disk DMA only
1036 libata.dma=2 ATAPI (CDROM) DMA only
1037 libata.dma=4 Compact Flash DMA only
1038 Combinations also work, so libata.dma=3 enables DMA
1039 for disks and CDROMs, but not CFs.
1040
1041 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1042 when set.
1043 Format: <int>
1044
1045 libata.force= [LIBATA] Force configurations. The format is comma
1046 separated list of "[ID:]VAL" where ID is
1047 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1048 matching port, link or device. Basically, it matches
1049 the ATA ID string printed on console by libata. If
1050 the whole ID part is omitted, the last PORT and DEVICE
1051 values are used. If ID hasn't been specified yet, the
1052 configuration applies to all ports, links and devices.
1053
1054 If only DEVICE is omitted, the parameter applies to
1055 the port and all links and devices behind it. DEVICE
1056 number of 0 either selects the first device or the
1057 first fan-out link behind PMP device. It does not
1058 select the host link. DEVICE number of 15 selects the
1059 host link and device attached to it.
1060
1061 The VAL specifies the configuration to force. As long
1062 as there's no ambiguity shortcut notation is allowed.
1063 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1064 The following configurations can be forced.
1065
1066 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1067 Any ID with matching PORT is used.
1068
1069 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1070
1071 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1072 udma[/][16,25,33,44,66,100,133] notation is also
1073 allowed.
1074
1075 * [no]ncq: Turn on or off NCQ.
1076
1077 If there are multiple matching configurations changing
1078 the same attribute, the last one is used.
1079
1080 load_ramdisk= [RAM] List of ramdisks to load from floppy
1081 See Documentation/ramdisk.txt.
1082
1083 lockd.nlm_grace_period=P [NFS] Assign grace period.
1084 Format: <integer>
1085
1086 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1087 Format: <integer>
1088
1089 lockd.nlm_timeout=T [NFS] Assign timeout value.
1090 Format: <integer>
1091
1092 lockd.nlm_udpport=M [NFS] Assign UDP port.
1093 Format: <integer>
1094
1095 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1096 Format: <irq>
1097
1098 loglevel= All Kernel Messages with a loglevel smaller than the
1099 console loglevel will be printed to the console. It can
1100 also be changed with klogd or other programs. The
1101 loglevels are defined as follows:
1102
1103 0 (KERN_EMERG) system is unusable
1104 1 (KERN_ALERT) action must be taken immediately
1105 2 (KERN_CRIT) critical conditions
1106 3 (KERN_ERR) error conditions
1107 4 (KERN_WARNING) warning conditions
1108 5 (KERN_NOTICE) normal but significant condition
1109 6 (KERN_INFO) informational
1110 7 (KERN_DEBUG) debug-level messages
1111
1112 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1113 Format: { n | nk | nM }
1114 n must be a power of two. The default size
1115 is set in the kernel config file.
1116
1117 logo.nologo [FB] Disables display of the built-in Linux logo.
1118 This may be used to provide more screen space for
1119 kernel log messages and is useful when debugging
1120 kernel boot problems.
1121
1122 lp=0 [LP] Specify parallel ports to use, e.g,
1123 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1124 lp=reset first parallel port). 'lp=0' disables the
1125 lp=auto printer driver. 'lp=reset' (which can be
1126 specified in addition to the ports) causes
1127 attached printers to be reset. Using
1128 lp=port1,port2,... specifies the parallel ports
1129 to associate lp devices with, starting with
1130 lp0. A port specification may be 'none' to skip
1131 that lp device, or a parport name such as
1132 'parport0'. Specifying 'lp=auto' instead of a
1133 port specification list means that device IDs
1134 from each port should be examined, to see if
1135 an IEEE 1284-compliant printer is attached; if
1136 so, the driver will manage that printer.
1137 See also header of drivers/char/lp.c.
1138
1139 lpj=n [KNL]
1140 Sets loops_per_jiffy to given constant, thus avoiding
1141 time-consuming boot-time autodetection (up to 250 ms per
1142 CPU). 0 enables autodetection (default). To determine
1143 the correct value for your kernel, boot with normal
1144 autodetection and see what value is printed. Note that
1145 on SMP systems the preset will be applied to all CPUs,
1146 which is likely to cause problems if your CPUs need
1147 significantly divergent settings. An incorrect value
1148 will cause delays in the kernel to be wrong, leading to
1149 unpredictable I/O errors and other breakage. Although
1150 unlikely, in the extreme case this might damage your
1151 hardware.
1152
1153 ltpc= [NET]
1154 Format: <io>,<irq>,<dma>
1155
1156 mac5380= [HW,SCSI] Format:
1157 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1158
1159 machvec= [IA64] Force the use of a particular machine-vector
1160 (machvec) in a generic kernel.
1161 Example: machvec=hpzx1_swiotlb
1162
1163 max_loop= [LOOP] Maximum number of loopback devices that can
1164 be mounted
1165 Format: <1-256>
1166
1167 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1168 should make use of. maxcpus=n : n >= 0 limits the
1169 kernel to using 'n' processors. n=0 is a special case,
1170 it is equivalent to "nosmp", which also disables
1171 the IO APIC.
1172
1173 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1174 equal to this physical address is ignored.
1175
1176 max_luns= [SCSI] Maximum number of LUNs to probe.
1177 Should be between 1 and 2^32-1.
1178
1179 max_report_luns=
1180 [SCSI] Maximum number of LUNs received.
1181 Should be between 1 and 16384.
1182
1183 mcatest= [IA-64]
1184
1185 mce [X86-32] Machine Check Exception
1186
1187 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1188
1189 md= [HW] RAID subsystems devices and level
1190 See Documentation/md.txt.
1191
1192 mdacon= [MDA]
1193 Format: <first>,<last>
1194 Specifies range of consoles to be captured by the MDA.
1195
1196 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1197 Amount of memory to be used when the kernel is not able
1198 to see the whole system memory or for test.
1199 [X86-32] Use together with memmap= to avoid physical
1200 address space collisions. Without memmap= PCI devices
1201 could be placed at addresses belonging to unused RAM.
1202
1203 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1204 memory.
1205
1206 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1207 E820 memory map, as specified by the user.
1208 Such memmap=exactmap lines can be constructed based on
1209 BIOS output or other requirements. See the memmap=nn@ss
1210 option description.
1211
1212 memmap=nn[KMG]@ss[KMG]
1213 [KNL] Force usage of a specific region of memory
1214 Region of memory to be used, from ss to ss+nn.
1215
1216 memmap=nn[KMG]#ss[KMG]
1217 [KNL,ACPI] Mark specific memory as ACPI data.
1218 Region of memory to be used, from ss to ss+nn.
1219
1220 memmap=nn[KMG]$ss[KMG]
1221 [KNL,ACPI] Mark specific memory as reserved.
1222 Region of memory to be used, from ss to ss+nn.
1223 Example: Exclude memory from 0x18690000-0x1869ffff
1224 memmap=64K$0x18690000
1225 or
1226 memmap=0x10000$0x18690000
1227
1228 memtest= [KNL,X86] Enable memtest
1229 Format: <integer>
1230 range: 0,4 : pattern number
1231 default : 0 <disable>
1232
1233 meye.*= [HW] Set MotionEye Camera parameters
1234 See Documentation/video4linux/meye.txt.
1235
1236 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1237 Multi-Function General Purpose Timers on AMD Geode
1238 platforms.
1239
1240 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1241 the BIOS has incorrectly applied a workaround. TinyBIOS
1242 version 0.98 is known to be affected, 0.99 fixes the
1243 problem by letting the user disable the workaround.
1244
1245 mga= [HW,DRM]
1246
1247 mminit_loglevel=
1248 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1249 parameter allows control of the logging verbosity for
1250 the additional memory initialisation checks. A value
1251 of 0 disables mminit logging and a level of 4 will
1252 log everything. Information is printed at KERN_DEBUG
1253 so loglevel=8 may also need to be specified.
1254
1255 mousedev.tap_time=
1256 [MOUSE] Maximum time between finger touching and
1257 leaving touchpad surface for touch to be considered
1258 a tap and be reported as a left button click (for
1259 touchpads working in absolute mode only).
1260 Format: <msecs>
1261 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1262 reporting absolute coordinates, such as tablets
1263 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1264 reporting absolute coordinates, such as tablets
1265
1266 mpu401= [HW,OSS]
1267 Format: <io>,<irq>
1268
1269 MTD_Partition= [MTD]
1270 Format: <name>,<region-number>,<size>,<offset>
1271
1272 MTD_Region= [MTD] Format:
1273 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1274
1275 mtdparts= [MTD]
1276 See drivers/mtd/cmdlinepart.c.
1277
1278 mtdset= [ARM]
1279 ARM/S3C2412 JIVE boot control
1280
1281 See arch/arm/mach-s3c2412/mach-jive.c
1282
1283 mtouchusb.raw_coordinates=
1284 [HW] Make the MicroTouch USB driver use raw coordinates
1285 ('y', default) or cooked coordinates ('n')
1286
1287 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1288
1289 NCR_D700= [HW,SCSI]
1290 See header of drivers/scsi/NCR_D700.c.
1291
1292 ncr5380= [HW,SCSI]
1293
1294 ncr53c400= [HW,SCSI]
1295
1296 ncr53c400a= [HW,SCSI]
1297
1298 ncr53c406a= [HW,SCSI]
1299
1300 ncr53c8xx= [HW,SCSI]
1301
1302 netdev= [NET] Network devices parameters
1303 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1304 Note that mem_start is often overloaded to mean
1305 something different and driver-specific.
1306 This usage is only documented in each driver source
1307 file if at all.
1308
1309 nf_conntrack.acct=
1310 [NETFILTER] Enable connection tracking flow accounting
1311 0 to disable accounting
1312 1 to enable accounting
1313 Default value depends on CONFIG_NF_CT_ACCT that is
1314 going to be removed in 2.6.29.
1315
1316 nfsaddrs= [NFS]
1317 See Documentation/filesystems/nfsroot.txt.
1318
1319 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1320 See Documentation/filesystems/nfsroot.txt.
1321
1322 nfs.callback_tcpport=
1323 [NFS] set the TCP port on which the NFSv4 callback
1324 channel should listen.
1325
1326 nfs.idmap_cache_timeout=
1327 [NFS] set the maximum lifetime for idmapper cache
1328 entries.
1329
1330 nfs.enable_ino64=
1331 [NFS] enable 64-bit inode numbers.
1332 If zero, the NFS client will fake up a 32-bit inode
1333 number for the readdir() and stat() syscalls instead
1334 of returning the full 64-bit number.
1335 The default is to return 64-bit inode numbers.
1336
1337 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1338 when a NMI is triggered.
1339 Format: [state][,regs][,debounce][,die]
1340
1341 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1342
1343 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1344 emulation library even if a 387 maths coprocessor
1345 is present.
1346
1347 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1348 caches in the slab allocator. Saves per-node memory,
1349 but will impact performance.
1350
1351 noalign [KNL,ARM]
1352
1353 noapic [SMP,APIC] Tells the kernel to not make use of any
1354 IOAPICs that may be present in the system.
1355
1356 nobats [PPC] Do not use BATs for mapping kernel lowmem
1357 on "Classic" PPC cores.
1358
1359 nocache [ARM]
1360
1361 nodelayacct [KNL] Disable per-task delay accounting
1362
1363 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1364
1365 noefi [X86-32,X86-64] Disable EFI runtime services support.
1366
1367 noexec [IA-64]
1368
1369 noexec [X86-32,X86-64]
1370 On X86-32 available only on PAE configured kernels.
1371 noexec=on: enable non-executable mappings (default)
1372 noexec=off: disable non-executable mappings
1373
1374 noexec32 [X86-64]
1375 This affects only 32-bit executables.
1376 noexec32=on: enable non-executable mappings (default)
1377 read doesn't imply executable mappings
1378 noexec32=off: disable non-executable mappings
1379 read implies executable mappings
1380
1381 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1382 register save and restore. The kernel will only save
1383 legacy floating-point registers on task switch.
1384
1385 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1386
1387 nohlt [BUGS=ARM]
1388
1389 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1390 instruction doesn't work correctly and not to
1391 use it.
1392
1393 nohalt [IA-64] Tells the kernel not to use the power saving
1394 function PAL_HALT_LIGHT when idle. This increases
1395 power-consumption. On the positive side, it reduces
1396 interrupt wake-up latency, which may improve performance
1397 in certain environments such as networked servers or
1398 real-time systems.
1399
1400 nohz= [KNL] Boottime enable/disable dynamic ticks
1401 Valid arguments: on, off
1402 Default: on
1403
1404 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1405
1406 noirqdebug [X86-32] Disables the code which attempts to detect and
1407 disable unhandled interrupt sources.
1408
1409 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1410 broken timer IRQ sources.
1411
1412 noisapnp [ISAPNP] Disables ISA PnP code.
1413
1414 noinitrd [RAM] Tells the kernel not to load any configured
1415 initial RAM disk.
1416
1417 nointroute [IA-64]
1418
1419 nojitter [IA64] Disables jitter checking for ITC timers.
1420
1421 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1422
1423 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1424
1425 noltlbs [PPC] Do not use large page/tlb entries for kernel
1426 lowmem mapping on PPC40x.
1427
1428 nomca [IA-64] Disable machine check abort handling
1429
1430 nomce [X86-32] Machine Check Exception
1431
1432 nomfgpt [X86-32] Disable Multi-Function General Purpose
1433 Timer usage (for AMD Geode machines).
1434
1435 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1436
1437 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1438 with UP alternatives
1439
1440 noresidual [PPC] Don't use residual data on PReP machines.
1441
1442 noresume [SWSUSP] Disables resume and restores original swap
1443 space.
1444
1445 no-scroll [VGA] Disables scrollback.
1446 This is required for the Braillex ib80-piezo Braille
1447 reader made by F.H. Papenmeier (Germany).
1448
1449 nosbagart [IA-64]
1450
1451 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1452
1453 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1454 and disable the IO APIC. legacy for "maxcpus=0".
1455
1456 nosoftlockup [KNL] Disable the soft-lockup detector.
1457
1458 nosync [HW,M68K] Disables sync negotiation for all devices.
1459
1460 notsc [BUGS=X86-32] Disable Time Stamp Counter
1461
1462 nousb [USB] Disable the USB subsystem
1463
1464 nowb [ARM]
1465
1466 nptcg= [IA64] Override max number of concurrent global TLB
1467 purges which is reported from either PAL_VM_SUMMARY or
1468 SAL PALO.
1469
1470 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1471 one of ['zone', 'node', 'default'] can be specified
1472 This can be set from sysctl after boot.
1473 See Documentation/sysctl/vm.txt for details.
1474
1475 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1476
1477 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1478 Rather than timing out after 20 ms if an EC
1479 command is not properly ACKed, override the length
1480 of the timeout. We have interrupts disabled while
1481 waiting for the ACK, so if this is set too high
1482 interrupts *may* be lost!
1483
1484 opl3= [HW,OSS]
1485 Format: <io>
1486
1487 oprofile.timer= [HW]
1488 Use timer interrupt instead of performance counters
1489
1490 osst= [HW,SCSI] SCSI Tape Driver
1491 Format: <buffer_size>,<write_threshold>
1492 See also Documentation/scsi/st.txt.
1493
1494 panic= [KNL] Kernel behaviour on panic
1495 Format: <timeout>
1496
1497 parkbd.port= [HW] Parallel port number the keyboard adapter is
1498 connected to, default is 0.
1499 Format: <parport#>
1500 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1501 0 for XT, 1 for AT (default is AT).
1502 Format: <mode>
1503
1504 parport= [HW,PPT] Specify parallel ports. 0 disables.
1505 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1506 Use 'auto' to force the driver to use any
1507 IRQ/DMA settings detected (the default is to
1508 ignore detected IRQ/DMA settings because of
1509 possible conflicts). You can specify the base
1510 address, IRQ, and DMA settings; IRQ and DMA
1511 should be numbers, or 'auto' (for using detected
1512 settings on that particular port), or 'nofifo'
1513 (to avoid using a FIFO even if it is detected).
1514 Parallel ports are assigned in the order they
1515 are specified on the command line, starting
1516 with parport0.
1517
1518 parport_init_mode= [HW,PPT]
1519 Configure VIA parallel port to operate in
1520 a specific mode. This is necessary on Pegasos
1521 computer where firmware has no options for setting
1522 up parallel port mode and sets it to spp.
1523 Currently this function knows 686a and 8231 chips.
1524 Format: [spp|ps2|epp|ecp|ecpepp]
1525
1526 pas2= [HW,OSS] Format:
1527 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1528
1529 pas16= [HW,SCSI]
1530 See header of drivers/scsi/pas16.c.
1531
1532 pause_on_oops=
1533 Halt all CPUs after the first oops has been printed for
1534 the specified number of seconds. This is to be used if
1535 your oopses keep scrolling off the screen.
1536
1537 pcbit= [HW,ISDN]
1538
1539 pcd. [PARIDE]
1540 See header of drivers/block/paride/pcd.c.
1541 See also Documentation/paride.txt.
1542
1543 pci=option[,option...] [PCI] various PCI subsystem options:
1544 off [X86-32] don't probe for the PCI bus
1545 bios [X86-32] force use of PCI BIOS, don't access
1546 the hardware directly. Use this if your machine
1547 has a non-standard PCI host bridge.
1548 nobios [X86-32] disallow use of PCI BIOS, only direct
1549 hardware access methods are allowed. Use this
1550 if you experience crashes upon bootup and you
1551 suspect they are caused by the BIOS.
1552 conf1 [X86-32] Force use of PCI Configuration
1553 Mechanism 1.
1554 conf2 [X86-32] Force use of PCI Configuration
1555 Mechanism 2.
1556 noaer [PCIE] If the PCIEAER kernel config parameter is
1557 enabled, this kernel boot option can be used to
1558 disable the use of PCIE advanced error reporting.
1559 nodomains [PCI] Disable support for multiple PCI
1560 root domains (aka PCI segments, in ACPI-speak).
1561 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1562 Configuration
1563 nomsi [MSI] If the PCI_MSI kernel config parameter is
1564 enabled, this kernel boot option can be used to
1565 disable the use of MSI interrupts system-wide.
1566 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1567 routing table. These calls are known to be buggy
1568 on several machines and they hang the machine
1569 when used, but on other computers it's the only
1570 way to get the interrupt routing table. Try
1571 this option if the kernel is unable to allocate
1572 IRQs or discover secondary PCI buses on your
1573 motherboard.
1574 rom [X86-32] Assign address space to expansion ROMs.
1575 Use with caution as certain devices share
1576 address decoders between ROMs and other
1577 resources.
1578 norom [X86-32,X86_64] Do not assign address space to
1579 expansion ROMs that do not already have
1580 BIOS assigned address ranges.
1581 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1582 assigned automatically to PCI devices. You can
1583 make the kernel exclude IRQs of your ISA cards
1584 this way.
1585 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1586 of the PIRQ table (normally generated
1587 by the BIOS) if it is outside the
1588 F0000h-100000h range.
1589 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1590 useful if the kernel is unable to find your
1591 secondary buses and you want to tell it
1592 explicitly which ones they are.
1593 assign-busses [X86-32] Always assign all PCI bus
1594 numbers ourselves, overriding
1595 whatever the firmware may have done.
1596 usepirqmask [X86-32] Honor the possible IRQ mask stored
1597 in the BIOS $PIR table. This is needed on
1598 some systems with broken BIOSes, notably
1599 some HP Pavilion N5400 and Omnibook XE3
1600 notebooks. This will have no effect if ACPI
1601 IRQ routing is enabled.
1602 noacpi [X86-32] Do not use ACPI for IRQ routing
1603 or for PCI scanning.
1604 use_crs [X86-32] Use _CRS for PCI resource
1605 allocation.
1606 routeirq Do IRQ routing for all PCI devices.
1607 This is normally done in pci_enable_device(),
1608 so this option is a temporary workaround
1609 for broken drivers that don't call it.
1610 skip_isa_align [X86] do not align io start addr, so can
1611 handle more pci cards
1612 firmware [ARM] Do not re-enumerate the bus but instead
1613 just use the configuration from the
1614 bootloader. This is currently used on
1615 IXP2000 systems where the bus has to be
1616 configured a certain way for adjunct CPUs.
1617 noearly [X86] Don't do any early type 1 scanning.
1618 This might help on some broken boards which
1619 machine check when some devices' config space
1620 is read. But various workarounds are disabled
1621 and some IOMMU drivers will not work.
1622 bfsort Sort PCI devices into breadth-first order.
1623 This sorting is done to get a device
1624 order compatible with older (<= 2.4) kernels.
1625 nobfsort Don't sort PCI devices into breadth-first order.
1626 cbiosize=nn[KMG] The fixed amount of bus space which is
1627 reserved for the CardBus bridge's IO window.
1628 The default value is 256 bytes.
1629 cbmemsize=nn[KMG] The fixed amount of bus space which is
1630 reserved for the CardBus bridge's memory
1631 window. The default value is 64 megabytes.
1632
1633 pcmv= [HW,PCMCIA] BadgePAD 4
1634
1635 pd. [PARIDE]
1636 See Documentation/paride.txt.
1637
1638 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1639 boot time.
1640 Format: { 0 | 1 }
1641 See arch/parisc/kernel/pdc_chassis.c
1642
1643 pf. [PARIDE]
1644 See Documentation/paride.txt.
1645
1646 pg. [PARIDE]
1647 See Documentation/paride.txt.
1648
1649 pirq= [SMP,APIC] Manual mp-table setup
1650 See Documentation/i386/IO-APIC.txt.
1651
1652 plip= [PPT,NET] Parallel port network link
1653 Format: { parport<nr> | timid | 0 }
1654 See also Documentation/parport.txt.
1655
1656 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1657 Override pmtimer IOPort with a hex value.
1658 e.g. pmtmr=0x508
1659
1660 pnpacpi= [ACPI]
1661 { off }
1662
1663 pnpbios= [ISAPNP]
1664 { on | off | curr | res | no-curr | no-res }
1665
1666 pnp_reserve_irq=
1667 [ISAPNP] Exclude IRQs for the autoconfiguration
1668
1669 pnp_reserve_dma=
1670 [ISAPNP] Exclude DMAs for the autoconfiguration
1671
1672 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1673 Ranges are in pairs (I/O port base and size).
1674
1675 pnp_reserve_mem=
1676 [ISAPNP] Exclude memory regions for the
1677 autoconfiguration.
1678 Ranges are in pairs (memory base and size).
1679
1680 print-fatal-signals=
1681 [KNL] debug: print fatal signals
1682 print-fatal-signals=1: print segfault info to
1683 the kernel console.
1684 default: off.
1685
1686 printk.time= Show timing data prefixed to each printk message line
1687 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1688
1689 profile= [KNL] Enable kernel profiling via /proc/profile
1690 Format: [schedule,]<number>
1691 Param: "schedule" - profile schedule points.
1692 Param: <number> - step/bucket size as a power of 2 for
1693 statistical time based profiling.
1694 Param: "sleep" - profile D-state sleeping (millisecs).
1695 Requires CONFIG_SCHEDSTATS
1696 Param: "kvm" - profile VM exits.
1697
1698 processor.max_cstate= [HW,ACPI]
1699 Limit processor to maximum C-state
1700 max_cstate=9 overrides any DMI blacklist limit.
1701
1702 processor.nocst [HW,ACPI]
1703 Ignore the _CST method to determine C-states,
1704 instead using the legacy FADT method
1705
1706 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1707 before loading.
1708 See Documentation/ramdisk.txt.
1709
1710 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1711 probe for; one of (bare|imps|exps|lifebook|any).
1712 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1713 per second.
1714 psmouse.resetafter= [HW,MOUSE]
1715 Try to reset the device after so many bad packets
1716 (0 = never).
1717 psmouse.resolution=
1718 [HW,MOUSE] Set desired mouse resolution, in dpi.
1719 psmouse.smartscroll=
1720 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1721 0 = disabled, 1 = enabled (default).
1722
1723 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1724 Format:
1725 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1726
1727 pt. [PARIDE]
1728 See Documentation/paride.txt.
1729
1730 pty.legacy_count=
1731 [KNL] Number of legacy pty's. Overwrites compiled-in
1732 default number.
1733
1734 quiet [KNL] Disable most log messages
1735
1736 r128= [HW,DRM]
1737
1738 raid= [HW,RAID]
1739 See Documentation/md.txt.
1740
1741 ramdisk_blocksize= [RAM]
1742 See Documentation/ramdisk.txt.
1743
1744 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1745 See Documentation/ramdisk.txt.
1746
1747 rcupdate.blimit= [KNL,BOOT]
1748 Set maximum number of finished RCU callbacks to process
1749 in one batch.
1750
1751 rcupdate.qhimark= [KNL,BOOT]
1752 Set threshold of queued
1753 RCU callbacks over which batch limiting is disabled.
1754
1755 rcupdate.qlowmark= [KNL,BOOT]
1756 Set threshold of queued RCU callbacks below which
1757 batch limiting is re-enabled.
1758
1759 rdinit= [KNL]
1760 Format: <full_path>
1761 Run specified binary instead of /init from the ramdisk,
1762 used for early userspace startup. See initrd.
1763
1764 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1765 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1766 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1767
1768 relax_domain_level=
1769 [KNL, SMP] Set scheduler's default relax_domain_level.
1770 See Documentation/cpusets.txt.
1771
1772 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1773
1774 reservetop= [X86-32]
1775 Format: nn[KMG]
1776 Reserves a hole at the top of the kernel virtual
1777 address space.
1778
1779 reset_devices [KNL] Force drivers to reset the underlying device
1780 during initialization.
1781
1782 resume= [SWSUSP]
1783 Specify the partition device for software suspend
1784
1785 resume_offset= [SWSUSP]
1786 Specify the offset from the beginning of the partition
1787 given by "resume=" at which the swap header is located,
1788 in <PAGE_SIZE> units (needed only for swap files).
1789 See Documentation/power/swsusp-and-swap-files.txt
1790
1791 retain_initrd [RAM] Keep initrd memory after extraction
1792
1793 rhash_entries= [KNL,NET]
1794 Set number of hash buckets for route cache
1795
1796 riscom8= [HW,SERIAL]
1797 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1798
1799 ro [KNL] Mount root device read-only on boot
1800
1801 root= [KNL] Root filesystem
1802
1803 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1804 mount the root filesystem
1805
1806 rootflags= [KNL] Set root filesystem mount option string
1807
1808 rootfstype= [KNL] Set root filesystem type
1809
1810 rootwait [KNL] Wait (indefinitely) for root device to show up.
1811 Useful for devices that are detected asynchronously
1812 (e.g. USB and MMC devices).
1813
1814 root_plug.vendor_id=
1815 [ROOTPLUG] Override the default vendor ID
1816
1817 root_plug.product_id=
1818 [ROOTPLUG] Override the default product ID
1819
1820 root_plug.debug=
1821 [ROOTPLUG] Enable debugging output
1822
1823 rw [KNL] Mount root device read-write on boot
1824
1825 S [KNL] Run init in single mode
1826
1827 sa1100ir [NET]
1828 See drivers/net/irda/sa1100_ir.c.
1829
1830 sbni= [NET] Granch SBNI12 leased line adapter
1831
1832 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1833 Format: <io>[,<timeout>[,<isapnp>]]
1834
1835 scsi_debug_*= [SCSI]
1836 See drivers/scsi/scsi_debug.c.
1837
1838 scsi_default_dev_flags=
1839 [SCSI] SCSI default device flags
1840 Format: <integer>
1841
1842 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1843 Format: <vendor>:<model>:<flags>
1844 (flags are integer value)
1845
1846 scsi_logging_level= [SCSI] a bit mask of logging levels
1847 See drivers/scsi/scsi_logging.h for bits. Also
1848 settable via sysctl at dev.scsi.logging_level
1849 (/proc/sys/dev/scsi/logging_level).
1850 There is also a nice 'scsi_logging_level' script in the
1851 S390-tools package, available for download at
1852 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1853
1854 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1855 discovered. async scans them in kernel threads,
1856 allowing boot to proceed. none ignores them, expecting
1857 user space to do the scan.
1858
1859 selinux [SELINUX] Disable or enable SELinux at boot time.
1860 Format: { "0" | "1" }
1861 See security/selinux/Kconfig help text.
1862 0 -- disable.
1863 1 -- enable.
1864 Default value is set via kernel config option.
1865 If enabled at boot time, /selinux/disable can be used
1866 later to disable prior to initial policy load.
1867
1868 selinux_compat_net =
1869 [SELINUX] Set initial selinux_compat_net flag value.
1870 Format: { "0" | "1" }
1871 0 -- use new secmark-based packet controls
1872 1 -- use legacy packet controls
1873 Default value is 0 (preferred).
1874 Value can be changed at runtime via
1875 /selinux/compat_net.
1876
1877 serialnumber [BUGS=X86-32]
1878
1879 shapers= [NET]
1880 Maximal number of shapers.
1881
1882 sim710= [SCSI,HW]
1883 See header of drivers/scsi/sim710.c.
1884
1885 simeth= [IA-64]
1886 simscsi=
1887
1888 slram= [HW,MTD]
1889
1890 slub_debug[=options[,slabs]] [MM, SLUB]
1891 Enabling slub_debug allows one to determine the
1892 culprit if slab objects become corrupted. Enabling
1893 slub_debug can create guard zones around objects and
1894 may poison objects when not in use. Also tracks the
1895 last alloc / free. For more information see
1896 Documentation/vm/slub.txt.
1897
1898 slub_max_order= [MM, SLUB]
1899 Determines the maximum allowed order for slabs.
1900 A high setting may cause OOMs due to memory
1901 fragmentation. For more information see
1902 Documentation/vm/slub.txt.
1903
1904 slub_min_objects= [MM, SLUB]
1905 The minimum number of objects per slab. SLUB will
1906 increase the slab order up to slub_max_order to
1907 generate a sufficiently large slab able to contain
1908 the number of objects indicated. The higher the number
1909 of objects the smaller the overhead of tracking slabs
1910 and the less frequently locks need to be acquired.
1911 For more information see Documentation/vm/slub.txt.
1912
1913 slub_min_order= [MM, SLUB]
1914 Determines the mininum page order for slabs. Must be
1915 lower than slub_max_order.
1916 For more information see Documentation/vm/slub.txt.
1917
1918 slub_nomerge [MM, SLUB]
1919 Disable merging of slabs with similar size. May be
1920 necessary if there is some reason to distinguish
1921 allocs to different slabs. Debug options disable
1922 merging on their own.
1923 For more information see Documentation/vm/slub.txt.
1924
1925 smart2= [HW]
1926 Format: <io1>[,<io2>[,...,<io8>]]
1927
1928 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1929 attempt to substitute SMP alternatives once at boot.
1930
1931 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1932 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1933 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1934 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1935 smsc-ircc2.ircc_irq= [HW] IRQ line
1936 smsc-ircc2.ircc_dma= [HW] DMA channel
1937 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1938 0: Toshiba Satellite 1800 (GP data pin select)
1939 1: Fast pin select (default)
1940 2: ATC IRMode
1941
1942 snd-ad1816a= [HW,ALSA]
1943
1944 snd-ad1848= [HW,ALSA]
1945
1946 snd-ali5451= [HW,ALSA]
1947
1948 snd-als100= [HW,ALSA]
1949
1950 snd-als4000= [HW,ALSA]
1951
1952 snd-azt2320= [HW,ALSA]
1953
1954 snd-cmi8330= [HW,ALSA]
1955
1956 snd-cmipci= [HW,ALSA]
1957
1958 snd-cs4231= [HW,ALSA]
1959
1960 snd-cs4232= [HW,ALSA]
1961
1962 snd-cs4236= [HW,ALSA]
1963
1964 snd-cs4281= [HW,ALSA]
1965
1966 snd-cs46xx= [HW,ALSA]
1967
1968 snd-dt019x= [HW,ALSA]
1969
1970 snd-dummy= [HW,ALSA]
1971
1972 snd-emu10k1= [HW,ALSA]
1973
1974 snd-ens1370= [HW,ALSA]
1975
1976 snd-ens1371= [HW,ALSA]
1977
1978 snd-es968= [HW,ALSA]
1979
1980 snd-es1688= [HW,ALSA]
1981
1982 snd-es18xx= [HW,ALSA]
1983
1984 snd-es1938= [HW,ALSA]
1985
1986 snd-es1968= [HW,ALSA]
1987
1988 snd-fm801= [HW,ALSA]
1989
1990 snd-gusclassic= [HW,ALSA]
1991
1992 snd-gusextreme= [HW,ALSA]
1993
1994 snd-gusmax= [HW,ALSA]
1995
1996 snd-hdsp= [HW,ALSA]
1997
1998 snd-ice1712= [HW,ALSA]
1999
2000 snd-intel8x0= [HW,ALSA]
2001
2002 snd-interwave= [HW,ALSA]
2003
2004 snd-interwave-stb=
2005 [HW,ALSA]
2006
2007 snd-korg1212= [HW,ALSA]
2008
2009 snd-maestro3= [HW,ALSA]
2010
2011 snd-mpu401= [HW,ALSA]
2012
2013 snd-mtpav= [HW,ALSA]
2014
2015 snd-nm256= [HW,ALSA]
2016
2017 snd-opl3sa2= [HW,ALSA]
2018
2019 snd-opti92x-ad1848=
2020 [HW,ALSA]
2021
2022 snd-opti92x-cs4231=
2023 [HW,ALSA]
2024
2025 snd-opti93x= [HW,ALSA]
2026
2027 snd-pmac= [HW,ALSA]
2028
2029 snd-rme32= [HW,ALSA]
2030
2031 snd-rme96= [HW,ALSA]
2032
2033 snd-rme9652= [HW,ALSA]
2034
2035 snd-sb8= [HW,ALSA]
2036
2037 snd-sb16= [HW,ALSA]
2038
2039 snd-sbawe= [HW,ALSA]
2040
2041 snd-serial= [HW,ALSA]
2042
2043 snd-sgalaxy= [HW,ALSA]
2044
2045 snd-sonicvibes= [HW,ALSA]
2046
2047 snd-sun-amd7930=
2048 [HW,ALSA]
2049
2050 snd-sun-cs4231= [HW,ALSA]
2051
2052 snd-trident= [HW,ALSA]
2053
2054 snd-usb-audio= [HW,ALSA,USB]
2055
2056 snd-via82xx= [HW,ALSA]
2057
2058 snd-virmidi= [HW,ALSA]
2059
2060 snd-wavefront= [HW,ALSA]
2061
2062 snd-ymfpci= [HW,ALSA]
2063
2064 softlockup_panic=
2065 [KNL] Should the soft-lockup detector generate panics.
2066
2067 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2068 See Documentation/sonypi.txt
2069
2070 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2071 See Documentation/specialix.txt.
2072
2073 spia_io_base= [HW,MTD]
2074 spia_fio_base=
2075 spia_pedr=
2076 spia_peddr=
2077
2078 sscape= [HW,OSS]
2079 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2080
2081 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2082 See Documentation/scsi/st.txt.
2083
2084 sti= [PARISC,HW]
2085 Format: <num>
2086 Set the STI (builtin display/keyboard on the HP-PARISC
2087 machines) console (graphic card) which should be used
2088 as the initial boot-console.
2089 See also comment in drivers/video/console/sticore.c.
2090
2091 sti_font= [HW]
2092 See comment in drivers/video/console/sticore.c.
2093
2094 stifb= [HW]
2095 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2096
2097 sunrpc.pool_mode=
2098 [NFS]
2099 Control how the NFS server code allocates CPUs to
2100 service thread pools. Depending on how many NICs
2101 you have and where their interrupts are bound, this
2102 option will affect which CPUs will do NFS serving.
2103 Note: this parameter cannot be changed while the
2104 NFS server is running.
2105
2106 auto the server chooses an appropriate mode
2107 automatically using heuristics
2108 global a single global pool contains all CPUs
2109 percpu one pool for each CPU
2110 pernode one pool for each NUMA node (equivalent
2111 to global on non-NUMA machines)
2112
2113 swiotlb= [IA-64] Number of I/O TLB slabs
2114
2115 switches= [HW,M68k]
2116
2117 sym53c416= [HW,SCSI]
2118 See header of drivers/scsi/sym53c416.c.
2119
2120 sysrq_always_enabled
2121 [KNL]
2122 Ignore sysrq setting - this boot parameter will
2123 neutralize any effect of /proc/sys/kernel/sysrq.
2124 Useful for debugging.
2125
2126 t128= [HW,SCSI]
2127 See header of drivers/scsi/t128.c.
2128
2129 tdfx= [HW,DRM]
2130
2131 test_suspend= [SUSPEND]
2132 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2133 standby suspend) as the system sleep state to briefly
2134 enter during system startup. The system is woken from
2135 this state using a wakeup-capable RTC alarm.
2136
2137 thash_entries= [KNL,NET]
2138 Set number of hash buckets for TCP connection
2139
2140 thermal.act= [HW,ACPI]
2141 -1: disable all active trip points in all thermal zones
2142 <degrees C>: override all lowest active trip points
2143
2144 thermal.crt= [HW,ACPI]
2145 -1: disable all critical trip points in all thermal zones
2146 <degrees C>: lower all critical trip points
2147
2148 thermal.nocrt= [HW,ACPI]
2149 Set to disable actions on ACPI thermal zone
2150 critical and hot trip points.
2151
2152 thermal.off= [HW,ACPI]
2153 1: disable ACPI thermal control
2154
2155 thermal.psv= [HW,ACPI]
2156 -1: disable all passive trip points
2157 <degrees C>: override all passive trip points to this value
2158
2159 thermal.tzp= [HW,ACPI]
2160 Specify global default ACPI thermal zone polling rate
2161 <deci-seconds>: poll all this frequency
2162 0: no polling (default)
2163
2164 tmscsim= [HW,SCSI]
2165 See comment before function dc390_setup() in
2166 drivers/scsi/tmscsim.c.
2167
2168 tp720= [HW,PS2]
2169
2170 trix= [HW,OSS] MediaTrix AudioTrix Pro
2171 Format:
2172 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2173
2174 turbografx.map[2|3]= [HW,JOY]
2175 TurboGraFX parallel port interface
2176 Format:
2177 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2178 See also Documentation/input/joystick-parport.txt
2179
2180 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2181 See header of drivers/scsi/u14-34f.c.
2182
2183 uart401= [HW,OSS]
2184 Format: <io>,<irq>
2185
2186 uart6850= [HW,OSS]
2187 Format: <io>,<irq>
2188
2189 uhci-hcd.ignore_oc=
2190 [USB] Ignore overcurrent events (default N).
2191 Some badly-designed motherboards generate lots of
2192 bogus events, for ports that aren't wired to
2193 anything. Set this parameter to avoid log spamming.
2194 Note that genuine overcurrent events won't be
2195 reported either.
2196
2197 unknown_nmi_panic
2198 [X86-32,X86-64]
2199 Set unknown_nmi_panic=1 early on boot.
2200
2201 usbcore.autosuspend=
2202 [USB] The autosuspend time delay (in seconds) used
2203 for newly-detected USB devices (default 2). This
2204 is the time required before an idle device will be
2205 autosuspended. Devices for which the delay is set
2206 to a negative value won't be autosuspended at all.
2207
2208 usbhid.mousepoll=
2209 [USBHID] The interval which mice are to be polled at.
2210
2211 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2212 kernel's map of available physical RAM.
2213
2214 vdso= [X86-32,SH,x86-64]
2215 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2216 vdso=1: enable VDSO (default)
2217 vdso=0: disable VDSO mapping
2218
2219 vdso32= [X86-32,X86-64]
2220 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2221 vdso32=1: enable 32-bit VDSO (default)
2222 vdso32=0: disable 32-bit VDSO mapping
2223
2224 vector= [IA-64,SMP]
2225 vector=percpu: enable percpu vector domain
2226
2227 video= [FB] Frame buffer configuration
2228 See Documentation/fb/modedb.txt.
2229
2230 vga= [BOOT,X86-32] Select a particular video mode
2231 See Documentation/i386/boot.txt and
2232 Documentation/svga.txt.
2233 Use vga=ask for menu.
2234 This is actually a boot loader parameter; the value is
2235 passed to the kernel using a special protocol.
2236
2237 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2238 size of <nn>. This can be used to increase the
2239 minimum size (128MB on x86). It can also be used to
2240 decrease the size and leave more room for directly
2241 mapped kernel RAM.
2242
2243 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2244 Format: <command>
2245
2246 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2247 Format: <command>
2248
2249 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2250 Format: <command>
2251
2252 waveartist= [HW,OSS]
2253 Format: <io>,<irq>,<dma>,<dma2>
2254
2255 wd33c93= [HW,SCSI]
2256 See header of drivers/scsi/wd33c93.c.
2257
2258 wd7000= [HW,SCSI]
2259 See header of drivers/scsi/wd7000.c.
2260
2261 wdt= [WDT] Watchdog
2262 See Documentation/watchdog/wdt.txt.
2263
2264 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2265 xd_geo= See header of drivers/block/xd.c.
2266
2267 xirc2ps_cs= [NET,PCMCIA]
2268 Format:
2269 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2270
2271 norandmaps Don't use address space randomization
2272 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2273
2274 ______________________________________________________________________
2275
2276 TODO:
2277
2278 Add documentation for ALSA options.
2279 Add more DRM drivers.